Generic scissors-type frames are known from the prior art and have been widely used in particular in the field of motor vehicles. In this field, they serve not only for adjusting the height of a seat in a motor vehicle, but also as a means of suspension for in particular increasing the seating comfort for a vehicle driver and ensuring a good seating comfort for example when the vehicle is moving over uneven ground.
Height-adjustable vehicle seats are often also provided with an air spring, wherein such an air spring can be influenced in terms of its spring effect by means of additional volumes which are usually arranged outside the air spring. By way of example, a required additional air volume can be pumped into a first abutment region of the air spring in order thereby to increase a degree of damping of the spring accordingly and to prevent the air spring from reaching its abutment. In addition or as an alternative, an additional air volume can be removed from an opposite abutment region and can be conveyed if necessary into an additional volume tank. This results in a large number of adjustment possibilities. In the case of such air springs for vehicle seats, therefore, often at least one external additional volume tank is required, which must be connected to the air spring as a separate unit by means of further air connections. Such additional volume tanks must be arranged as additional elements within the vehicle seat and thus take up additional space.
However, due to the desired compression of their parts in order to reduce their space requirement within the vehicle, such height-adjustable vehicle seats are often being designed with an increasingly small base frame, resulting in the problem of the presence of a sufficient amount of space for such an additional volume tank.
It should furthermore be emphasized that previously known scissors-type frames for vehicle seats with relatively large suspensions and relatively large spring travels provided exclusively multiple-component rockers with welded-in axles or tubes for bearing purposes, as a result of which in particular the risk of manufacturing tolerances usually increases.
By way of example, the document DE 10 2006 017 774 A1 discloses a vehicle seat with a height-adjustable seat frame, which comprises at least two seat frame parts that can move relative to one another and at least one gas spring which is arranged between the seat frame parts for the purpose of height adjustment, wherein at least one control device for influencing the gas spring is provided. The control device comprises at least one valve device which is attached to a first seat frame part and which comprises control valves for actuating gas flows for the gas spring, and also a control slide which is provided on a second seat frame part and which is intended for actuating the control valves, so that a pre-settable height of the vehicle seat is ensured regardless of a weight loading of the vehicle seat. This is a vehicle seat in which the control slide can be adjusted relative to the second seat frame part by means of an adjustment device regardless of a relative position of the seat frame parts, so that a movement of the control slide relative to the second seat frame part which is brought about by the adjustment device brings about a height adjustment of the vehicle seat. Therefore, although a height adjustment of the vehicle seat can be achieved in a simple manner, nevertheless the production of such a seat requires a relatively complicated construction comprising numerous components.
From the further document DE 43 35 199 C1 it is known to provide a sprung vehicle seat with a scissors-type frame which comprises scissors elements that can pivot about a common scissors axle. For adjusting the scissors-type frame, a gas spring is provided, to which there can be connected a first valve device for adjusting the height of the vehicle seat and, via a coupling, a second valve device for setting the height of the driver's seat in a weight-dependent manner. The coupling comprises a segment element with an arc-shaped toothed section, which is pivotable about the scissors axis, and a pivoting arm with a toothing which can be brought into meshing engagement with the toothed section. The pivoting arm is connected to one of the scissors elements and can be actuated by means of a drive device which is connected to the first valve device. Also arranged pivotably on the scissors axle is a slide element which serves for actuating the second valve device and which is movable to a limited extent relative to the segment element. This construction is also very complicated.
A simplified substructure for a vehicle seat with a scissors-type frame comprising two pivotable frame elements is described in European patent EP 0 563 948 B1. Here, the two pivotable frame elements of the scissors-type frame are not fixedly connected to one another but rather merely bear against one another. There is therefore no need for welded-in axles or tubes for bearing the two frame elements relative to one another. As a result, the scissors-type frame can be of relatively simple design, but the frame elements do not form a coherent unit, which means that in particular the assembly of the scissors-type frame can take place only in conjunction with a base element and a seat plate. Moreover, no space is provided for an air or gas pressure damper.